better documentation for string reversal #23793
Conversation
stevengj
added
docs
| "êxa" | ||
|
|
||
| julia> join(reverse(collect(graphemes("ax̂e")))) # reverses graphemes | ||
| "ex̂a" |
There was a problem hiding this comment.
The hat is shown in the wrong place in github's diff display in by browser, but if I paste it into my terminal it is correct. Apparently their display of combining characters is broken?
github:
copy/paste from github into a Julia session in a terminal:
copy/paste from github into Atom:
base/strings/types.jl
Outdated
| regex (regular expression) searches. See also [`reverseind`](@ref) to convert indices | ||
| in `s` to indices in `reverse(s)` and vice-versa, and [`graphemes`](@ref) | ||
| to operate on user-visible "characters" (graphemes) rather than codepoints | ||
| (which is more [visually pleasing but less useful](https://github.com/JuliaLang/julia/issues/6165) for reverse searching). |
There was a problem hiding this comment.
I wouldn't refer to GitHub issues in the official docs. Anyway people are unlikely to use graphemes unless they have a reason to, given that it's easier to iterate over/reverse codepoints.
base/strings/types.jl
Outdated
| @@ -117,10 +117,23 @@ end | |||
|
|
|||
| Reverses a string. | |||
|
|
|||
| Technically, this function reverses the "codepoints" in a string, and its | |||
| main utility is for reversed-order string processing, especially for reversed | |||
| regex (regular expression) searches. See also [`reverseind`](@ref) to convert indices | |||
There was a problem hiding this comment.
Just "regular expression"? Also, which use quotes around "codepoints"?
base/strings/types.jl
Outdated
| @@ -131,7 +144,7 @@ reverse(s::RevString) = s.string | |||
| """ | |||
| reverseind(v, i) | |||
|
|
|||
| Given an index `i` in `reverse(v)`, return the corresponding index in `v` so that | |||
| Given an index `i` in [`reverse(v)`](@ref), return the corresponding index in `v` so that | |||
| `v[reverseind(v,i)] == reverse(v)[i]`. (This can be nontrivial in the case where `v` is a | |||
| Unicode string.) | |||
There was a problem hiding this comment.
BTW, "Unicode string" is a weird terminology since now all strings support Unicode. Maybe just remove that sentence? Or say that it's nontrivial because of non-ASCII characters.
In looking back at #6165 (due to #23612), I realized that we never clearly documented the behavior or rationale.